Police Raid Occupy Oakland Tents

The site was indeed down for hours, and we were unable to access the site after multiple attempts.

If Anonymous was responsible -- there's no official confirmation -- it most likely used distributed denial of services attacks, or DDoS, Gizmodo reported. Basically, this type of attack overloads servers until they crash.

Occupy Oakland Protests Port

Anonymous has gained notoriety in the Bay Area after multiple recent incidents.

"Anonymous has been watching," the hacker group wrote on its website. "Since the inception of Occupy Oakland, we have been actively monitoring your behavior, and exposing the identities and sensitive information of officers of the Oakland Police Department; as they have continued to act in an unprofessional and violent manner."

And last August, BART turned off cell phone service at several San Francisco stations to limit communication between people protesting the July 3 shooting death of Charles Hill. Hill was a homeless man BART officers said had a knife.

Last week, Anonymous took credit for briefly shutting down websites of the U.S. Department of Homeland Security and the FBI, but the CIA seems to be a popular target. A group affiliated with Anonymous also went after cia.gov, shutting the site down for a few hours last June.